In drag racing, the car engines need to be adjusted between races. One of the key maintenance tasks is to adjust the valves. To make these adjustments, the valve cover must be removed. The valve cover is typically secured by from four to eight bolts. Thus, to remove the valve cover, all the bolts must first be removed. When finished, the valve cover must be replaced along with the bolts. Removing the bolts becomes a time consuming step in the maintenance process. Typically, on a race day, these adjustments may have to be made four or five times. Saving time can improve pit crew performance by reducing stress on the crew.
Several types of quick release bolts have been developed. These bolts all have been developed for specific purposes and do not have the proper characteristics needed for this type of operation. Such bolt designs, however, are illustrative of the types of methods used to achieve the quick release operation. For example, U.S. Pat. No. 2,377,086 to Lang teaches a quick release apparatus for temporarily holding metal plates or sheets together. In this design, a shaft is provided that is inserted into a housing. A spring is loaded into the housing around the shaft. An operating handle is attached to the top of the shaft. Two pivoting teeth are rotatably mounted to the shaft. The device is used by pushing the housing through holes drilled in two plates that are then aligned. Under the operating handle is a holding plate that remains on the other side of the plates from the housing and the teeth. Once the housing is properly set, the operating handle is engaged, which causes the teeth to rotate out of the housing through two holes. The engagement of the teeth, which are curved as in a cam causes the plates to be pulled tightly together. Releasing the handle causes the teeth to withdraw, thereby allowing the plates to be separated.
U.S. Pat. No. 3,873,162 to Segawa illustrates a similar type quick release mechanism for bicycle wheels. Instead of the teeth of Lang, the Segawa design uses friction clips that engage bolt threads. The friction clips can be released when desired, releasing the bolt, which allows the wheel to be removed easily.
U.S. Pat. No. 4,974,888 to Childers illustrates another method of quick release mechanism. In this design, a nut is split and held in place by an expandable framework. The nut has teeth that correspond to the bolt. For quick release operation in the case of a secured bolt, the nut is caused to expand around the bolt, leaving the bolt unfettered by the threads. This allows the bolt to be quickly pulled from the nut. Similarly, to fasten the system, the bolt is pushed into the nut, causing the nut to expand. Once the bolt is in position, the nut closes around the bolt, creating a tight lock. This design is also intended to secure two parts together (i.e., a vending machine door and the frame). The design allows the bolt to be turned within the nut to further tighten the parts as desired.
A similar design in U.S. Pat. No. 4,930,961 to Weis teaches a design similar to the Childers design in that it uses a split bolt. Here, the bolt is a fixed stud mounted to a member. A workpiece is placed over the stud bolt and the nut can then be placed on the bolt above the workpiece. The nut is split to allow it to pass around the bolt threads quickly. Once the nut is flush against the workpiece, it engages the threads on the bolt. Then, the nut secures the workpiece and holds it securely. Additional tightening can be done once the nut has engaged the threads.
U.S. Pat. No. 5,123,794 to Pire is a quick release mechanism for use in space vehicles. Unlike the split nut designs above, this design uses a threaded stud that is secured into a body using a threaded well. The stud has a top extension that has a number of annular teeth. A grip arm is provided that can open and close about the annular teeth. The grip arm is operated hydraulically. To remove the assembly from the stud, the hydraulics operate the grip arm, which opened about the teeth, thereby allowing the assembly to be removed. The assembly can be reinstalled by causing the grip arm to open, sliding the assembly over the stud bolt and then closing the grip arm around the teeth. The stud bolt can then be removed by turning the bolt in the usual manner.
Finally, U.S. Pat. No. 5,205,693 to Fuller et al. teaches a quick release bolt for use with power lawn mower blades. In this design, two pins are used to secure the bolt in position on the mower. If the pins are removed, the bolt can be quickly removed. This device also includes a threaded adjustment mechanism so that the bolt seats with the proper tension to hole the mower blade securely.